A series of azaperylene derivatives such as monoazaperylene (MAPery), 1,6-diazaperylene (1,6-DiAPery), 1,7-diazaperylene (1,7-DiAPery), 1,12-diazaperylene (1,12-DiAPery), triazaperylene (TriAPery), and tetraazaperylene (TetAPery) was synthesized by changing the position and number of nitrogen atoms at the bay region of a perylene skeleton in 1, 6, 7, and 12 positions. The density functional theory (DFT) calculations and electrochemical measurements suggested that the energies of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) states significantly become stabilized with increasing the number of nitrogen atoms, whereas the estimated HOMO–LUMO gaps approximately remain constant. This result is in good agreement with the absorption and fluorescence spectral measurements. Additionally, these steady-state spectroscopic measurements demonstrate the broadened spectra as compared to pristine perylene (Pery). In photophysical measurements, the fluorescence quantum yields (ΦFL) significantly decreased as the number of nitrogen atoms increased, whereas much enhanced quantum yields and rate constants of internal conversion (ΦIC and k IC) were observed. Especially, the increased k IC values of TriAPery (k IC: ∼108 s–1) and TetAPery (k IC: ∼109 s–1) are much larger than those of diazaperylene and monoazaperylene derivatives (k IC: ∼107 s–1). These photophysical trends were successfully explained by time-dependent DFT (TD-DFT) calculations. Finally, the characteristic protonated and deprotonated processes of nitrogen atoms in azaperylenes under acidic conditions were monitored utilizing absorption and fluorescence measurements. The binding constants demonstrate that the nitrogen atoms at 1 and 12 positions of a perylene skeleton are essential for the increased values.
As eries of terrylene derivatives, such as monoazaterrylene (MATe rry), 1,6-diazaterrylene (DiATe rry) and pristine terrylene (Terry), were synthesized by changing the number of nitrogen atoms at the bay region (1 and 6p ositions of the Terry core). The electrochemical measurements suggested that the first one-electronreductionand oxidation potentials becamep ositivelys hifted with increasing numberso f nitrogen atoms. This agreedw ith the energies of the corresponding highest occupied molecularo rbital (HOMO) and lowest unoccupied molecular orbital (LUMO) states estimated by DFT methods. In contrast, the HOMO-LUMO gaps ap-proximately remained constant. This trend is quite similart o the spectroscopicb ehaviors observed by absorption and fluorescences pectra. The solvent polarity-dependent spectroscopic trends of DiATerry suggested the intramolecular charge-transfer (ICT) characters. Thee valuation of the excited-state dynamics in variouss olvents indicated the electronic configurational changes of the excited states relative to the ground state via the ICT.T his was supported by the Lippert-Matagap lots. Finally, the reversible protonation and deprotonation processes were also observed.
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